Self propelled projectile with fins

ABSTRACT

The invention relates to a fin arrangement for a self-propelled projectile which comprises a sleeve mounted coaxially and slidingly over the rear part of the venture of the projectile. The fins are hinged to said sleeve. The sleeve is displaced under the acceleration force of the projectile, after having left the launching tube, from a forward rest position to a rearward service position. This rectilinear displacement of the sleeve causes the unfolding of the fins, the rear part of which are guided by means of guiding ramps, fast with the projectile, during said displacement.

[ June 25, 1974 United States Patent [191 Rusbach Primary ExaminerVerlin R. Pendegrass Attorney, Agent, or FirmYoung & Thompson FINS [ SELF PROPELLED PROJECTILE WITH [75] Inventor: Maurice Rusbach, Vernier-Geneva,

Switzerland Assignee: Sarmac S.A., Carouge-Geneva,

ABSTRACT Switzerland 221 Filed: Feb. 21, 1973 211 Appl. No.: 334,213

The invention relates to a tin arrangement for a selfa sleeve mounted coaxially and slidingly over the rear part of [52] US. Cl. 244/328 [51] Int Cl F42b 13/32 [58] Field of Search........................... 244/327, 3.28

ward service position. This rectilinear displacement of the sleeve causes the unfolding of the fins, the rear part of which are guided by means of guiding ramps, fast with the projectile, during said displacement.

[56] References Cited UNITED STATES PATENTS 3,684,2l4 8/1972 244/327 3,690,595 9/1972 Rusback 244/327 FOREIGN PATENTS OR APPLICATIONS 12 Claims, 13 Drawing Figures 1,418,696 l0ll965 France...............................

PATENTEU JURZS I974 SHEET 1 [IF 5 PATENTED JUNZ 5 I974 i A A saw u [if s FIG. 9

FIG. /0

PATENTEU JUNZ S1974 SHEET 5 BF 5 SELF PROPELLED PROJECTILE WITH F INS In order to impart the best possible position to the self-propelled projectiles provided with expanding fin arrangements, the propulsive acceleration of which continues after they have left their launching tube, it is important that the aerodynamic stabilisation be obtained very rapidly, that is to say that the fins expand the least possible distance during the continuing of the propulsion of the said projectiles outside of their launching tube.

The invention relates to a self-propelled projectile provided with a fin arrangement of simple construction which is light and of low cost.

This projectile can be long and approximately of the same calibre as its launching tube. Its fin arrangement is designed in order to be housed when folded in a relatively small space comprised for example between one or several venturis and the launching tube.

The expanding or unfolding of this fin arrangement has the advantage of being caused by the effect of the propulsive acceleration of the projectile. It is symmetrical with respect to the axis of the projectile, the opening of the fins is synchronized and their displacement is not reversible. The expanding of this fin arrangement which is carried out as soon as the projectile leaves the launching tube, along its trajectory, is not caused by the pressure of the propulsion gazes of the projectile, by its gyration force, by springs or any other complicated and fragile devices.

When the projectile has only one rear coaxial venturi, the fins may in the expanded state, be disposed longitudinally around this venturi. As long as the selfpropelled projectile is within its launching tube, its fin arrangement has not the possibility to lock or wedge itself, since locking means such as a mechanical element maintains it in its place. Only a certain friction along the launching tube may result from the locking pieces.

The invention has for its object a self-propelled projectile provided with a fin arrangement intended to be fixed by means of a launching tube, provided with a rearwardly folded fin arrangement which unfolds rapidly under the effect of the acceleration of the projectile when it has left the launching tube.

This projectile is characterized by the fact that its fin arrangement comprises a sleeve mounted coaxially and slidingly along a rear part of the projectile, fins hinged on the said sliding sleeve and folded in rest position along the body of the projectile, their free ends being in the vicinity of the rear end of the projectile, locking means of the fin arrangement in this rest position when the projectile is within the launching tube and guiding ramps for the fins at the rear of the projectile, these ramps providing for the unfolding of the fins once the projectile has left the launching tube, when the fin arrangement is unlocked and the said fins are driven rearwardly by the said sleeve and slide on the said ramps under the effect of the acceleration of the projectile.

The stroke of the said sliding sleeve and of its fins is preferably limited by two end positions, one in the direction of the front of the projectile, which is occupied when the fin arrangement is locked, and the other rearwardly of the projectile which is occupied when the fins of the fin arrangement are completely unfolded, its displacement from the first to the second of these positions resulting from the acceleration effect of the projectile when it has left the launching tube.

Preferably the rear part of the projectile on which the said sleeve slides is constituted by its venturi or nozzel.

Preferably the tins of the fin arrangement are articulated on axes which are tangent to the sliding sleeve and are all located in a plan which is perpendicularly to the axis of the projectile.

The locking means of the fin arrangement may be constituted by a pawl hinged on each of the hinging axes of the fins, the beak of which engages in locking position of the fin arrangement in a groove which is provided in the outside wall of the venturi and is maintained in that position by its rear face in contact with the internal wall of the launching tube, so that it can be unlocked only once a projectile has left the launching tube.

The guiding ramps of the fins may be constituted by notches provided in a flange mounted on the ring of the free ends of the venturi in which the the said fins enter.

The locking means of the fin arrangement can further be constituted by a movable abutment resting on the one hand on a shoulder of the venturi end and on the other hand on a shoulder which is provided on each of the fins on its face turned towards the wall of the venturi.

The locking means of the fin arrangement may also be constituted by a stock hinged at the end of the venturi and folded on the end of each of the fins or further by tongues resting on the one hand on a rim of the end of the venturi and on the other hand on the end of the fins turned towards the wall of the launching tube.

The attached drawings show schematically and by way of example one embodiment of the projectile according to the invention and some variants of detail.

FIG. 1 shows the over-all projectile in elevation.

FIGS. 2 and 3 are end views representing respectively the fin arrangement folded and unfolded.

FIG. 4 is a partial view on a larger scale and in longitudinal cross-section showing the fin arrangement in folded condition.

FIG. 5 is a similar view to that of FIG. 4 representing the fin arrangement in its unfolded state.

FIG. 6 is a cross-section along line lV-IV of FIG. 4 of the folded fin arrangement.

FIGS. 7, 9 and 11 are views similar to that of FIG. 4 showing three variants of the fin arrangement in its folded state.

FIGS. 8 and 10 are views similar to that of FIG. 5

showing respectively the fin arrangements of FIGS. 7

and 9 in their unfolded state.

FIGS. 12 and 13 show one fin of the fin arrangement seen broadside and edgewise respectively.

The projectile shown in the drawings is a selfpropelled projectile comprising an explosive charge in front and a propulsive charge at the rear end 2. The propulsion gases escape through the coaxial venturi 3 on which is mounted in a slidable way a sleeve 4 on which are hinged four fins 5 applied at rest against the venturi 3 (see FIGS. 1, 2 and 4).

The sleeve 4 may slide freely on the venturi 3 between two limit positions as represented in FIGS. 4 and 5.

In the first of these two positions of the sleeve 4 (FIGS. 2 and 4), the fins 5 are folded onto the venturi 3 in order to permit the introduction of the projectile within the bore of a launching tube of a calibre corresponding to the calibre of the projectile and the sleeve 4 is maintained in its position by locks 6 hinged on the same axes 7 as the fins 5. These axes 7 to which the fins and the locks 6 are hinged are disposed tangently to the sliding sleeve 4 and are all located in a single plane perpendicular to the axis of the projectile. The locks 6 present a beak 8 entering in a groove 9 of the venturi and are maintained in this locking position of the fin arrangement by their outer face 10 which enters in contact with the internal wall of the launching tube when the projectile is within this launching tube. This outer face 10 of the locks 6 is sufficiently long on either side of its pivoting point to hinder any wedging during the firing.

In the second of the said two positions of the sleeve 4 (FIGS. 3 and 5), the fins 5 are unfolded due to their sliding rearwardly on their guiding ramps 11 during the displacement of the sleeve 4 from its first position (FIG. 4) to its second position, near the free end of the ventury 3. The said guiding ramps 11 are notches provided in a flange 12 mounted on a rim of the free end of the venturi 3, in which the edges of the fins are enter.

When the projectile has left the launching tube, the beaks 8 of the locks 6 are no more maintained in the groove of the venturi 3 by the pressure which was exerted by the internal wall of the launching tube on the rear face 10 of these locks.

Due to its inertia and under the effect of the acceleration of the projectile the sleeve 4 which is no more locked in its first position (FIG. 4) slides along the outside wall of the venturi 3 until it reaches its second position (FIG. 5) causing simultaneously the opening of the locks 6 and the unfolding of the fins 5 which are pushed rearwardly by said sleeve towards the rear of the projectile, sliding along the guiding ramps 11. In order to facilitate sliding along the external wall of the venturi 3, of the sleeve 4, said sleeve may be provided with two annular internal shoulders.

As seen in FIG. 4, the diameter of the folded fin arrangement is equal to the calibre of the projectile and this is essential to enable the introduction of the projectile into the bore of the launching tube having a diameter corresponding to the calibre of the projectile. However when unfolded the tin arrangement has a maximum diameter, at the ends of the fins 5, which is substantially greater than the calibre of the projectile, this ensuring to this projectile, a very good stability on a chosen trajectory (see FIGS. 3 and 5). On the other hand the unfolding of this fin arrangement is effected progressively and without any shock under the effect of the acceleration of the projectile thus contributing to the precision of the launching. The opening of the fins occurs very rapidly, as soon as the projectile comes out v of the launching tube, and to damp the shock when the sliding sleeve 4 comes to abut against the flange 12 mounted on the rim of the end of the venturi 3, a resilient ring 23 may be provided between the sleeve 4 and the flange 12 (see FIG. 12).

It is very important that the sleeve 4 and the fins 5 remain in locked position of the fin arrangement as long as the projectile is propelled within the launching tube in order to avoid any wedging.

To this effect other mechanical locking elements may be further provided:

As shown in FIG. 7, a mechanical locking element may be constituted by a movable abutment l3 resting on the one hand on a shoulder 14 which is provided on the end of the venturi 3 and on the other hand on a shoulder or turning 15 which is provided on the fins 5 located on their face or edge turned toward the wall of the venturi 3. The abutment 13 may be constituted advantageously by a spring blade, if desired provided with longitudinal notches, which is ejected when the fin arrangement is unfolded, as shown in FIG. 8. During their ejection, the abutment blades 13 contribute to the unfolding of the fins of the fin arrangement.

Another variant of the locking device of the fin arrangement may be constituted by a lock 16 hinged to the end of the venturi 3.

In locking position (FIG. 9), this lock 16 is folded onto the corresponding fin 5 and its beak 17 is located in alignment with the edge of the fin 5 which rests against the internal wall of the launching tube. Preferably the end of the fin will be formed in such a manner as to peirnit this alignment. In unlocked position (FIG. 10) the beak 17 of the lock 16 acts as a guiding ramp for the corresponding fin.

In the place of hinged locks at the end of the venturi, one may further provide rigid tongues 18 which can be ejected resting on the one hand on a rim 19 of the end of the venturi and on the other hand on the end of the fins 5 in front of the wall of the launching tube which is arranged in an appropriate way for this purpose. As is the case for the blade springs 13, the tongues 18 are ejected when the fin arrangement unfolds (see FIG. 2).

FIGS. 12 and 13 show a particularly advantageous shape for the fins due to their lightness and their rigidity. They are cut out from a steel plate which is folded on itself in such a manner as to present a resting plate 20 and a rib 21 the two flanges of which are connected by means of a rivet 22.

The fin arrangement described is particularly interesting due to its lightness, its rigidity, its simplicity and its precision. Since the fins, during their unfolding, move rearwardly with respect to the center of gravity of the projectile their stabilisation effect is further enhanced.

In order to avoid that the fins 5 of the fin arrangement will fold inadvertently after the launching of the projectile, one may further provide a locking device for the sleeve 4 in its position in which the fin arrangement is unfolded.

I claim: I t

l. A self-propelled projectile to be fired by means of a launching tube, a sleeve mounted coaxially and slidingly on a rear part of the projectile, elongated fins pivotally mounted on the sleeve adjacent their forward ends and extending rearwardly of the projectile to their free ends, said fins being swingable between a rest position in which the fins extend along the body of the projectile and an extended position in which the fins extend out beyond the caliber of the projectile, means for releasably retaining the fins in said rest position when the projectile is within a said launching tube, said sleeve sliding rearwardly of the projectile when the projectile has left the launching tube and accelerates, and means responsive to rearward sliding movement of the sleeve to move said fins from said rest position to said extended position.

2. A projectile as claimed in claim 1, and means limiting said sliding movement of said sleeve to a forward position in which said fins are in said rest position and a rearward position in which said fins are in said extended position.

3. A projectile as claimed in claim 1, the last-named means comprising guiding ramps along which said fins slide rearwardly and outwardly upon rearward sliding movement of said sleeve.

4. A projectile as claimed in claim 1, the last-named means comprising a flange at the rear of the projectile, said flange having notches therein in which the edges of said fins slide.

5. A projectile as claimed in claim 1, the diameter of said rear part of the projectile on which said sleeve slides being less than the caliber of said projectile.

6. A projectile as claimed in claim 4, said rear part of the projectile comprising an outer wall of a restricted opening through the rear of said projectile.

7. A projectile as claimed in claim 1, and resilient means at the rear end of the projectile against which said sleeve abuts when said sleeve reaches its rearrnost position.

8. A projectile as claimed in claim 1, the axes about which said fins pivot being tangential to said sleeve and being all disposed in a common plane perpendicular to the axis of the projectile.

9. A projectile as claimed in claim 1, said retaining means comprising a lock hinged on the pivotal axis of each fin, said lock having a beak which in locking position is disposed in a groove in said projectile, said lock having an outer surface that contacts the internal wall of a said launching tube thereby to hold said lock in said locking position until the projectile has left the launching tube.

10. A projectile as claimed in claim I, said retaining means comprising a movable abutment resting on a shoulder at the rear end of the projectile and on a shoulder on an inner side of the fins.

11. A projectile as claimed in claim 1, said retaining means comprising a lock hinged to the rear end of the projectile and folded over the end of each fin.

12. A projectile as claimed in claim 1, said retaining means comprising locks resting on the rim of the rear end of the projectile and on the ends of the fins. 

1. A self-propelled projectile to be fired by means of a launching tube, a sleeve mounted coaxially and slidingly on a rear part of the projectile, elongated fins pivotally mounted on the sleeve adjacent their forward ends and extending rearwardly of the projectile to their free ends, said fins being swingable between a rest position in which the fins extend along the body of the projectile and an extended position in which the fins extend out beyond the caliber of the projectile, means for releasably retaining the fins in said rest position when the projectile is within a said launching tube, said sleeve sliding rearwardly of the projectile when the projectile has left the launching tube and accelerates, and means responsive to rearward sliding movement of the sleeve to move said fins from said rest position to said extended position.
 2. A projectile as claimed in claim 1, and means limiting said sliding movement of said sleeve to a forward position in which said fins are in said rest position and a rearward position in which said fins are in said extended position.
 3. A projectile as claimed in claim 1, the last-named means comprising guiding ramps along which said fins slide rearwardly and outwardly upon rearward sliding movement of said sleeve.
 4. A projectile as claimed in claim 1, the last-named means comprising a flange at the rear of the projectile, said flange having notches therein in which the edges of said fins slide.
 5. A projectile as claimed in claim 1, the diameter of said rear part of the projectile on which said sleeve slides being less than the caliber of said projectile.
 6. A projectile as claimed in claim 4, said rear part of the projectile comprising an outer wall of a restricted opening through the rear of said projectile.
 7. A projectile as claimed in claim 1, and resilient means at the rear end of the projectile against which said sleeve abuts when said sleeve reaches its rearmost position.
 8. A projectile as claimed in claim 1, the axes about which said fins pivot being tangential to said sleeve and being all disposed in a common plane perpendicular to the axis of the projectile.
 9. A projectile as claimed in claim 1, said retaining means comprising a lock hinged on the pivotal axis of each fin, said lock having a beak which in locking position is disposed in a groove in said projectile, said lock having an outer surface that contacts the internal wall of a said launching tube thereby to hold said lock in said locking position until the projectile has left the launching tube.
 10. A projectile as claimed in claim 1, said retaining means comprising a movable abutment resting on a shoulder at the rear end of the projectile and on a shoulder on an inner side of the fins.
 11. A projectile as claimed in claim 1, said retaining means comprising a lock hinged to the rear end of the projectile and folded over the end of each fin.
 12. A projectile as claimed in claim 1, said retaining means comprising locks resting on the rim of the rear end of the projectile and on the ends of the fins. 